In Queens, 100,000 were tossed while 240,500 were vacated in Manhattan.

"Outstanding warrants for years-old, low-level cases drive law enforcement and communities apart," Manhattan district attorney Cyrus Vance said in a statement.

In the Bronx, 160,000 were dismissed.

"The people who have these warrants have not been in trouble with the law for a decade or more, and it is time that they are given the opportunity to live productive lives, free from summonses hanging over their heads," Bronx district attorney Darcel Clark said in a statement.

And in Brooklyn, applause rang out in a courtroom as 143,532 warrants were cleared.

"Someone who owes a $25 fine should not be arrested and brought down to central booking and spend 20 or 24 hours in a cell next to a hardened criminal. That's not fair, and that's not justice," said acting Brooklyn district attorney Eric Gonzalez after going to court himself to make the request and highlight the occasion.

The move -- requested by prosecutors and hailed by the mayor -- marks a sweeping step in city officials' efforts to promote what they see as a more fair and workable approach to low-level offenses.

The warrants date back a decade or longer and stem from summonses for nonviolent, small-scale offenses such as littering, open-container drinking, being in a park after hours or walking an unleashed dog.

"Those are lives we're talking about that are impacted. This is not just a number, there's a person behind that warrant," said New York City Council speaker Melissa Mark-Viverito.

The Guns of Chicago

Participating prosecutors say some people who get into fender-benders or even report a crime end up arrested over old summons warrants they didn't know about.

They're "law-abiding New Yorkers who committed a petty offense years ago and have not been in trouble with the law since," Vance said.

But their counterpart in Staten Island, district attorney Michael McMahon, says the dismissals are unfair to people who do show up in court.

"I believe that issuing blanket amnesty for these offenses is unfair to those citizens who responsibly appear in court and sends the wrong message about the importance of respecting our community and our laws," he said in a statement, noting that he's supported initiatives that invite people to appear in person to clear their records.

The prosecutors and mayor Bill de Blasio, a Democrat, also argued that arrests on such warrants tie up police time that could be better spent addressing more serious offenses.

Some other U.S. cities, from Atlanta to Las Vegas, have offered people the chance to clear up certain old warrants, often by paying fines.